Pulse oximeter sensor

ABSTRACT

The invention provides a pulse oximetry sensor for attachment to the lower half of the palm or the ulnar edge of the palm. The sensor may be portable, untethered and in some instances, disposable. The features of the sensor make it effective in stable, chronic or emergency medical settings.

CROSS REFERENCE TO RELATED APPLICATIONS

This application is a 35 U.S.C. § 371 U.S. National Stage Entry ofInternational Application No. PCT/US2013/074528 filed Dec. 12, 2013,entitled Pulse Oximeter Sensor, which claims the benefit of priority ofUS Provisional Patent Application No. 61/825,198 filed May 20, 2013,entitled Pulse Oximeter Sensor, the contents of which are eachincorporated herein by reference in its entirety.

FIELD OF THE INVENTION

The present invention is in the field of biotelemetry sensors andsystems and more specifically, pulse oximetry sensors and systems.

BACKGROUND OF THE INVENTION

Biotelemetry is the process of measuring biometric data. Telemetrysystems in the art have traditionally been focused on themulti-measurement and monitoring of biological statistics and have beentethered to large monitoring systems.

The present invention provides a pulse oximetry sensor and systemfocused on improvement at the “point of care” including improvements inportability, functionality and efficiency.

SUMMARY OF THE INVENTION

The present invention provides a pulse oximeter sensor for attachment tothe lower half of the palm or the ulnar edge of the palm

A pulse oximeter is a non-invasive medical device for measuringoxygenation of the blood. Oximetry involves the use of two light sourceshaving differing wavelengths (usually red at about 600 nm and infraredat about 900 nm). The light sources are sequentially passed through thepatient's body or a portion of a patient's body to a detector. Thedifference in absorbance of each of the two wavelengths is measured,allowing determination of the net absorbance as altered by the pulse ofarterial blood. The ratio of absorbance between the red and infraredlight caused by the variance between oxygenated and un-oxygenated blood(or hemoglobin status) is an indirect measure of the percent ofhemoglobin molecules bound with oxygen molecules.

A majority of pulse oximeters currently available on the market sufferfrom lack of a secure fit because they are primarily attached via a clipto the fingertip. Alternative sensor placement is possible and has beenreported for the toe, nose, forehead and ball of the foot. Wristoximeters are known in the art. Most of these, however, are limited tothe display module worn on the wrist like a wristwatch but with thesensor still placed on the tip of the finger and tethered to the wristband display. Pulse oximeters worn on the wrist with alternativeplacement of sensors, such as the sensor described in InternationalPatent Application No. WO2013030744 are also expected to suffer fromproblems arising due to relative motion of the dorsal part of the handwith respect to the wrist, which can cause alterations in signalsobtained from the sensors. Upward motion of the hand from a restingposition, for example, is one type of motion which can disturb readingsobtained from a pulse oximeter sensor placed on the wrist because thebase of the hand above the wrist crease impacts the edge of awristwatch-type sensor.

The present inventors have recognized the need for a pulse oximetersensor that can be worn on the hand at a position relatively free frommotions that interfere with the sensor signals, particularly motionsinvolving wrist flexion and curling of fingers in the process ofgripping. The present invention addresses this need, among others whichwill be discussed herein below.

In accordance with one aspect of the present invention, there isprovided a pulse oximetry sensor assembly for attachment to the lowerhalf of the palm or the ulnar edge of the palm, the sensor assemblycomprising: a) an elongate body supporting a light emitting source and adetector for detecting scattered light originating from the lightemitting source, wherein the light emitting source and the detector areconfigured to detect scattered light from a surface of the lower half ofthe palm or the ulnar edge of the palm; and b) a means for transmittingsignals corresponding to the scattered light acquired by the detector toa signal processing unit.

Another aspect of the invention provides a pulse oximetry systemcomprising: a) the pulse oximetry sensor assembly described herein; b) atransmission cable as the means for transmitting signals acquired by thedetector, the transmission cable in electrical communication with thedetector; and c) a signal processing unit in electrical communicationwith a display unit for displaying pulse oximetry readings.

Another aspect of the invention provides a kit comprising the sensorassembly described herein and instructions for attachment of the sensorassembly to the lower half of the palm or the ulnar edge of the palm.

Another aspect of the invention is a method for obtaining pulse oximetryreadings, the method comprising the steps of: a) attaching a pulseoximetry sensor to the palmar side of the ulnar edge of the palm betweenthe wrist crease and the base of the fifth digit, substantially parallelto a longitudinal axis defined by the fifth digit; b) connecting thesensor to a signal processing unit; and c) reading output data from thesignal processing unit.

Another aspect of the invention is a method for obtaining pulse oximetryreadings, the method comprising the steps of: a) attaching a pulseoximetry sensor to the palmar side of the ulnar edge of the palmadjacent the wrist crease and substantially parallel to a transverseaxis defined by the pisiform, lunate and scaphoid carpal bones; b)connecting the sensor to a signal processing unit; and c) reading outputdata from the signal processing unit.

Another aspect of the invention is a method for obtaining pulse oximetryreadings, the method comprising the steps of: a) attaching a pulseoximetry sensor to the of the ulnar edge of the palm substantiallyparallel to the longitudinal axis formed by the fifth digit; b)connecting the sensor to a signal processing unit; and c) reading outputdata from the signal processing unit.

Another aspect of the invention is a method for obtaining pulse oximetryreadings, the method comprising the steps of: a) attaching a pulseoximetry sensor to the lower half of the palm and substantially parallelto an axis defined by the scaphoid and trapezoid carpal bones and thefirst digit; b) connecting the sensor to a signal processing unit; andc) reading output data from the signal processing unit.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a schematic transparent top view of the pulse oximeter sensorassembly 10 of one particular embodiment of the present invention whichincludes a cover film 20, a protective pad 22 and a skin protecting pad24.

FIG. 2 is a cross sectional view taken along line 2′-2′ of FIG. 1 toillustrate the levels of the cover film 20, protective pad 22 and skinprotecting pad 24 with respect to the body of the sensor 12. The lightemitting source 14 is also shown.

FIG. 3 is a cross sectional view taken along line 3′-3′ of FIG. 1 toillustrate the levels of the cover film 20, the protective pad 22 andthe skin protecting pad 24 with respect to the body of the sensor 12.The detector 16 is also shown.

FIG. 4 is a cross sectional view taken along line 4′-4′ of FIG. 1 toillustrate the levels of the cover film 20, the protective pad 22 andthe skin protecting pad 24 with respect to the body of the sensor 12.The transmission cable 18 and the adhesive resin 30 are also shown.

FIG. 5 is a cross sectional view taken along line 5′-5′ of FIG. 1 toillustrate the levels of the cover film 20 and the protective pad 22with respect to the transmission cable 18 and the adhesive resin 30.

FIG. 6 is a semi-transparent top view of another embodiment of thesensor assembly 510 which includes a skin-contacting film 524, a coverfilm 520 and a radiofrequency/electromagnetic interference shield 515covering the detector.

FIG. 7 is a perspective exploded view of the sensor assembly 510 of FIG.6.

FIG. 8 is another top view (non-transparent) of the embodiment of thesensor assembly shown in FIGS. 6 and 7 showing how the position of thebody 512 (covered by an insulator strip 513) can be seen through theclear window 523 in the cover film 520.

FIG. 9 is a top view of a blank cutout 600 used to form one embodimentof the radiofrequency/electromagnetic interference shield of oneembodiment of the sensor assembly 510. The blank includes a first floorsection containing a Faraday window 601 and additional panels 602 and603 for forming floor sections as well as wall panels 611-617 and roofpanels 621-623.

FIG. 10 is a perspective view of a hand with fingers extended showingone possible placement of one embodiment of a sensor assembly 10 on thepalmar side of the ulnar edge of the palm UEP generally parallel to thefifth digit 5D and generally orthogonal to the wrist crease WC. Featuresof the sensor assembly 10 are omitted for clarity.

FIG. 11 is a perspective view of a hand with fingers extended showinganother possible placement of one embodiment of a sensor assembly 10 onthe palmar side of the ulnar edge of the palm UEP generally orthogonalto the fifth digit 5D and generally parallel to the wrist crease WC.Features of the sensor assembly 10 are omitted for clarity.

FIG. 12 is a perspective view of a hand with fingers extended showinganother possible placement of one embodiment of a sensor assembly 10 onthe ulnar edge of the palm UEP generally parallel to the fifth digit 5Dand generally orthogonal to the wrist crease WC. Features of the sensorassembly 10 are omitted for clarity.

FIG. 13 is a perspective view of a hand with fingers extended showinganother possible placement of one embodiment of a sensor assembly 10above the wrist crease WC along the axis formed by the scaphoid S, andtrapezoid Tz carpal bones and the first digit 1D. Features of the sensorassembly 10 are omitted for clarity.

FIG. 14 is perspective view of the skeleton of a hand showing onepossible placement of one embodiment of the sensor assembly 10 on thepalmar side of the ulnar edge of the palm. It can be seen that theelongate body 12 of the sensor assembly 10 lies opposed to the fifthmetacarpal SMC with some overlap of the fourth metacarpal, 4MC, and thehamate H, triquetrum T, lunate L and pisiform P carpal bones.

FIGS. 15A and 15B show system diagrams according to two embodiments of apulse oximetry system. In FIG. 15A, the sensor assembly 1000 isconnected to a signal processing unit 1130 by a transmission cable 1080which has plugs 1084 and 1086 for attachment and detachment of thetransmission cable 1080. The signal processing unit 1130 also hasconnections to a computer 1140 and a removable data storage unit 1150.In FIG. 15B, the system is similar to that of FIG. 15A except that thesensor is connected to a wireless transmitter 1172 for transmitting asignal 1170 from the sensor to a wireless receiver 1174.

FIG. 16 is a schematic diagram showing circuit details of a MASSIMO™connector, a red/infrared diode pair and a photo diode detector.

FIG. 17 is a schematic diagram showing circuit details of a NELLCOR™connector, a red/infrared diode pair and a photo diode detector.

DETAILED DESCRIPTION

The present invention provides a pulse oximetry sensor, as well as asystem and kit comprising the sensor. The present invention alsoprovides a method for obtaining pulse oximetry readings from the lowerhalf of the palm or the ulnar edge of the palm. The pulse oximetrysensor of various embodiments of the present invention may be used withsubjects of all ages from infants, including premature infants,pediatric patients, adults and the elderly. The system may comprisefeatures which help in the subject's comfort, mobility, and ease of usesuch as, but not limited to, hypoallergenic materials, flexiblematerials, size and shape options of the system, and the ability for thesensor to expand in order to accommodate swelling.

The system may further comprise features of being disposable andmodular. The pulse oximetry sensor of the present invention may bewireless (portable) and may be battery supported. Where a battery isemployed it is advantageous for the system to operate for long periodsof time. When data from the system are sent to a monitor, the reportsproduced may have the capability of producing graphs of prolonged datastreams or instant readouts. Monitors and graphing devices are wellknown in the art and can be used in conjunction with the pulse oximetersystem of the present invention.

The pulse oximeter sensor of the present invention has multiple uses inhealthcare. Non-limiting examples of uses for inpatient monitoringinclude hospitals such as pediatric hospitals, assisted livingfacilities, nursing homes, rehabilitation facilities, intensive careunits, respiratory departments, cardiac care centers, emergencydepartments and other specialized areas in medical facilities. In afurther embodiment, the pulse oximeter of the present invention may bemanufactured to be worn by a subject for extended periods of time andwill have optional features such as a skin protection pad for minimizingdiscomfort. The system may also be employed in the field in settingssuch as for example in military applications where soldiers are oftenseparated from direct healthcare providers. In this situation, theportable modular nature of the sensor allows for inclusion of the pulseoximeter system in a standard first aid kit and may be easy enough toemploy that any lay person can immediately attach it to an injuredperson and activate the system.

Certain embodiments of the pulse oximeter system may also provideinformation directly to the subject or to a user in the vicinity of thesubject. The subject or the user may trigger the system to gather orprovide information on the subject at a particular instance. In thiscase, the subject or the user would have access to an identifier buttonon the device that can be pushed to log a specific instance of aphysical symptom. When the identifier button is pushed, information suchas, but not limited to, the subject's vital statistics, the date and thetime may also be recorded so that the information can be assessed todetermine if there was a change in health status.

The modular nature of the sensor affords the health care professionalthe option of removing the sensor and replacing it with a new sensor.This aspect of the invention also aids in the reduction of nosocomialinfections and the spread of microorganisms under unsterile conditions.

Depending on the intended use, the pulse oximetry sensor may be used aspart of a system configured to record, save, and upload historical datafor clinical studies and patient information documentation. The systemmay be employed passively to measure vital statistics over a period oftime or may be triggered by an event or situation which captures one ormore metrics for storage or relay to a remote location. In this manner,the condition of a patient may be monitored for gradual or instantchanges in biometrics which can signal to the patient or to a healthcareprovider that one or more treatment regimens are needed.

Embodiments of the present invention will now be described withreference to the drawings. A number of features that may be incorporatedinto alternative embodiments will be described during the course of thedescription of the example embodiments. The skilled person willrecognize that these alternative embodiments are also within the scopeof the invention. Similar reference characters refer to similar partsthroughout the different views. The drawings are not necessarily toscale and emphasis is instead placed upon illustrating the principles ofthis particular embodiment and other aspects of the invention.

Features of a First Embodiment of the Sensor Assembly

Referring now to FIGS. 1-5 there is shown an embodiment of a pulseoximetry sensor assembly shown generally at 10. Sensor assembly 10includes an elongated body 12 which in some embodiments may be formed ofrigid plastic or other relatively rigid material appropriate for use asa substrate for a medical sensor. In other embodiments, the elongatedbody is not rigid and may be provided by a length of tape, as describedhereinbelow. In embodiments where a substantially rigid body isprovided, examples of plastics appropriate for constructing the body 12include, but are not limited to, polyethylene, polypropylene,polystyrene, polyester, polycarbonate, polyvinylchloride, nylon,poly(methyl methacrylate) and the like. The body 12 may be biodegradableand/or may be superabsorbent. These features are particularlyadvantageous in embodiments when the sensor assembly 10 is intended tobe for single use and disposable. In various embodiments, the body 12may have different lengths and widths which may be selected according tothe size of the hand of the individual for whom pulse oximetrymeasurements are desired. For example, a sensor body 12 may beconstructed for pediatric use which will have shorter lengths andwidths. In such pediatric uses, alternative placements of the sensorassembly may be applicable, particularly for infants who may requireplacement of the sensor assembly on a transverse or longitudinalposition of the foot, such as the heel, which is expected to providesimilar light scattering characteristics as the lower half of the palmor the ulnar edge of the palm. Additionally, a sensor body 12 of asensor assembly 10 constructed to fit an adult male may be longer andwider than a sensor intended for use by an adult female. In variousembodiments of the present invention therefore, the length of the body12 may range between about 30 mm to about 75 mm and range in widthbetween about 8 mm to about 15 mm. As used herein, the term “about”indicates a variation of plus or minus 10% of the value indicated.

A light emitting source 14 is supported by the body 12. The supportprovided by the body 12 may be provided by a housing, compartment orother such arrangement on or in the body or, alternatively, the lightemitting source 14 may simply rest upon the body 12. In certainembodiments, the light emitting source 14 is a light emitting diode(LED). Other embodiments may use other types of light emitters which areknown to those skilled in the art. In certain embodiments of theinvention, the LED is a bi-color LED which emits light at both 600 nmand 900 nm for example, an LED with part number SMT660/910 which iscommercially available from Epitex Inc. of Kyoto, Japan. Other LEDssuitable for use with the present invention are manufactured byHamamatsu Photonics (Hamamatsu, Japan—part numbers L5276, L5586, andL6286) and by OSI Optoelectronics Inc. (Hawthorne, Calif., USA);DLED-660/880-LLS-2 64/Leadless Ceramic 2 Leads/Back to Back,DLED-660/895-LLS-2 895, DLED-660/905-LLS-2 905, DLED-660/905-LLS-3 905 3Leads/Common Anode, DLED-660/940-LLS-3 940, DLED-660/880-CSL-2 88063/Side Locker Plastic, DLED-660/895-CSL-2 895 2 Leads/Back to Back,DLED-660/905-CSL-2 905, DLED-660/905-CSL-3 905 3 Leads/Common Anode, andDLED-660/940-CSL-3. Other LEDs are known to the skilled person and theseother LEDs may also be suitable for use as light emitting sources inalternative embodiments. The person skilled in the art knows how toconfigure these LEDs in combination with a sensor body such as body 12and that this may be done without undue experimentation. The skilledperson will also recognize that alternative embodiments may have twoseparate light emitting sources, with a first light emitting sourceconfigured to provide light for measuring light absorbance of oxygenatedblood and a second light emitting source configured to provide light formeasuring light absorbance of deoxygenated blood. In such alternativeembodiments, both light emitting sources are housed within or supportedon the body 12 at locations which may be determined by the skilledperson without undue experimentation.

In one embodiment, the light emitting source 14 may be positioned ortrained within its location in the elongate body 12 to emit light alongan angled path. Such an angle is shown in FIG. 2 and represented by thesymbol φ. In FIG. 2, light emitted orthogonal to the surface of thepalmar side of the ulnar edge of the palm UEP is indicated by L1 andlight emitted along the angled path is indicated by L2. For simplicity,only the scattering of L1 at the fifth metacarpal 5MC (for example) isshown as L3. It should be understood that L2 would also be expected toscatter from various other tissues in the lower half of the palm,particularly in the vicinity of the palmar side of the ulnar edge of thepalm or the ulnar edge of the palm itself, such as, for example,epidermis, dermis, tendons, muscles (such as the abductor and flexor ofthe digiti minimi), blood vessels (such as the ulnar artery), synovialfluid and bones. In cases where scattering from hard bone tissue occursas the predominant source of the scattering, the scattering is from oneor more of the bones located in the lower half of the palm or the ulnaredge of the palm, such as any of the five metacarpals, and any of thecarpals, including the pisiform, the scaphoid, the capitate, thetrapezoid, the trapezium, the scaphoid, the triquetrum, the lunate andthe hamate. The arrangements of the sensor with respect to the lowerhalf of the palm or the ulnar edge of the palm and the bones of thoselocations is indicated in FIGS. 10-14 and will be described in moredetail hereinbelow. The scattered light is differentially absorbed byoxygenated and deoxygenated blood vessels and it is this differentialabsorbance that forms the basis for pulse oximetry readings.

The body 12 also houses a detector 16 configured to detect light whichis emitted from the light emitting source 14 and scattered fromstructures of the palmar side of the ulnar edge of the palm UEP asindicated above. In one particular embodiment, the detector is a blueenhanced PIN silicon photodiode (Part No. PDV-C173SM), which iscommercially available from Advanced Photonics Inc. of Camarillo,Calif., USA. In other embodiments, the detector is a PIN-0.81-CSL 0.81mm² PIN diode photodetector type 60 with a molded frame (OSIOptoelectronics, Hawthorne, Calif., USA). This detector is matched to adual emitter LED. Other detectors include PIN-4.0-CSL or PIN-8.0-CSLphotodetectors which are also manufactured by OSI Optoelectronics. Theskilled person will recognize that other detectors may be selected andcan be adapted for use with certain embodiments of the present inventionwithout undue experimentation.

It is seen in FIG. 3 that scattered light L3 travels to the detector 16where it is converted to a signal that ultimately provides a measurementindicating the extent of oxygenation of blood.

In one embodiment, the linear distance from the center of the LED to thecenter of the detector is between about 8 mm to about 10 mm. In anotherembodiment, the linear distance from the center of the LED to the centerof the detector is about 9 mm. In another embodiment, the lineardistance from the center of the LED to the center of the detector is9.16 mm.

With reference to FIG. 1, it can be seen that the detector 16 isconnected to a transmission cable 18 for transmission of signalsobtained from the detector 16 which indicates the extent of lightabsorbance of deoxygenated and oxygenated blood. The skilled person willrecognize that the light emitting source requires a source of electricalpower. For the sake of clarity, this is not shown in FIGS. 1-5 but theskilled person will recognize that electrical power can be transmittedto the light emitting source by wires residing in the transmission cable18 and running across the body 12 to the light source 14. The signalsobtained at the detector 16 are transmitted through transmission cable18 to a signal processing unit (not shown in FIG. 1). The transmissioncable 18 may also hold the wires that provide electrical power to thelight emitting source 14. In two particular embodiments, transmissioncable 18 is provided with a 9-pin MASSIMO™ plug (as shown in FIG. 16)for connection to a MASSIMO™ monitor or is provided with a 9-pinNELLCOR™ plug (as shown in FIG. 17) for connection to a NELLCOR™monitor. In certain alternative embodiments, the transmission cable 18is detachable from the body 12 (see also the system diagram in FIG. 15Awhich will be described in more detail hereinbelow). Such alternativeembodiments are particularly advantageous when the sensor assembly 10 isintended to be disposable because the transmission cable 18 can be savedwhile the sensor assembly 10 is discarded after use. As an alternativeto a transmission cable 18, a wireless signal transmission system may beincorporated into sensor assembly 10 and its associated signalprocessing unit (see FIG. 15B). Such wireless systems, such asBluetooth, are well known to the skilled person and may be adapted foruse with certain embodiments of the present invention without undueexperimentation.

The particular embodiment of the sensor of the invention shown in FIG. 1includes layers of adhesive material and protective padding. The skilledperson will recognize that these features do not affect the generalsensing functions of the sensor assembly 10 and are provided to improvethe practicalities associated with attachment of the sensor assembly 10to the lower half of the palm or the ulnar edge of the palm UEP, such asprotection of the sensor assembly 10 from external impacts andprotection of the skin of the lower half of the palm or the ulnar edgeof the palm UEP to minimize discomfort. The relationships between thesefeatures with respect to the sensor body 12 are indicated in FIG. 1 andare also shown more clearly in cross sectional view in FIGS. 2-5(indicated by cross section lines 2′-2′, 3′-3′, 4′-4′ and 5′-5′ of FIG.1). In various embodiments, these layers of adhesive materials andpadding may be omitted from the construction of the sensor and replacedby materials which may be available in various healthcare settings, suchas gauze pads, bandages, medical grade tape and the like.

It can be seen in FIGS. 1-5 (wherein FIG. 1 which provides a transparenttop view of all layers), that a hexagonal-shaped protective pad 22 isprovided over the top surface of the sensor body 12. Rectangular oroval-shaped protective pads may also be used. The function of protectivepad 22 is simply to protect the sensor body 12 from external impacts.The materials used in the construction of such a protective pad 22 arecommercially available and are well known to the skilled person. Incertain embodiments, the protective pad 22 has a length of about 30 mmto about 75 mm and a width of about 10 mm to about 33 mm. In certainembodiments, the length is 65 mm. In certain embodiments, the width is30 mm. In some embodiments, the length is 65 mm and the width is 30 mm.

Affixed to the top surface of the protective pad 22 is a cover film 20which provides the function of fixing the sensor assembly to the lowerhalf of the palm or the ulnar edge of the palm UEP. The cover film 20 isshown with an oval-shaped dot-dashed line in FIG. 1. It is seen in thecross-sectional views of FIGS. 2-5 that the protective pad 22 issandwiched between the cover film 20 and the top surface of the sensorbody 12. The oval shape of the cover film 20 may be substituted forother shapes in alternative embodiments. In certain embodiments, thecover film 20 may be constructed of elastomeric plastic material such aselastomeric polyurethane, for example. The cover film 20 is coated witha suitable adhesive material for fixing the cover film 20 to the skin.Adhesives suitable for use with this elastomeric plastic material aremedical grade acrylic adhesives or synthetic rubber-based adhesiveswhich are well known to the person skilled in the art. Acrylic (oracrylate) adhesive has proven compatibility with skin and offers a rangeof performance characteristics and adhesion profiles. These types ofadhesives have low sensitization potential and are convenient for use inmanufacturing processes. Some examples of commercially adhesive filmmaterials which may be adapted for use as adhesive films of certainembodiments of the present invention include the materials used intransparent film medical dressings such as 3M Tegaderm™ and OpsiteFlexifit™ (Smith & Nephew, Memphis, Tenn., USA), the latter of which iswaterproof and provides resistance to growth of bacteria as well asminimizing the risk of skin damage upon removal. A series of medicaldressings formed of various plastics and provided with medical gradeadhesives, some of which are formed of materials appropriate for use informing the cover film 20 in various embodiments of the presentinvention, are described on the internet site www.dressings.com (thecontent of which is incorporated herein by reference in entirety). Thisinternet site is maintained by the Surgical Dressing Manufacturer'sAssociation (Chesterfield, UK). The skilled person has the knowledge toselect such commercially-available dressings from this list for use asadhesive films in various embodiments of the present invention. Suchselections may be made by the skilled person without undueexperimentation.

In certain embodiments, the cover film 20 has a length ranging betweenabout 75 mm to about 95 mm at its longest point and a width of about 40mm to about 75 mm at its widest point. In certain embodiments the widthof the cover film 20 is 60 mm. In certain embodiments, the length of thecover film 20 is 90 mm. In certain embodiments, the length and width ofthe cover film 20 are 90 mm and 60 mm, respectively.

In certain embodiments, the cover film 20 is provided with backing paper(not shown) to protect the adhesive surface of the cover film 20 priorto use. As indicated in FIG. 1, outer edges of the cover film 20 aredefined by lines 21 and the backing paper covering these outer edges isnon-adhesive peel paper which is easier to remove than the backing papercovering the remainder of the cover film 20. Once the non-adhesive peelpaper is removed, the remaining backing paper can then be easily removedfrom the cover film 20 without causing wrinkling of the cover film 20.

It may also be seen in FIG. 1, and in the cross-sectional views of FIGS.4 and 5, that the protective pad 22 and the cover film 20 also hold thetransmission cable 18 in place outside the proximal end 13 of the body12. In this embodiment, additional reinforcement of the transmissioncable 18 is provided by an extra adhesive film 30 such as a Scapasilicone adhesive pad (Scapa, Windsor, Conn., USA) or 3M Tegaderm™adhesive polymer film disposed on each side of the transmission cable18. The extra adhesive film 30 may also be added between the top of thetransmission cable 18 and the lower surface of the protective pad 22. Anappropriate adhesive film 30 may be selected from various commerciallyavailable adhesive films which are compatible with medical uses. Inalternative embodiments, other means for fixing the transmission cable18 in place may be used in place of the adhesive film 30 (such as gluesor other types of adhesive resins which are known to those skilled inthe art).

As seen in FIGS. 1-5, in this particular embodiment, a skin protectingpad 24 is affixed to the bottom surface of the body 12. The skinprotecting pad 24 may be constructed of medical grade polymers, woven ornon-woven cloths or fabrics or films provided with hypoallergenicsilicone adhesives such as the adhesives used in Scapa pads or Tegaderm™pads or other similar material suitable for protection of the skin frompossible irritations caused by contact with the body 12 and forprevention of trapping of heat against the ulnar surface of the palm.The skin protecting pad 24 is provided with openings 26 and 28 whichallow passage of light from the light emitting source 14 and to thedetector 16, respectively. The skin protecting pad 24 generally preventscontact of the skin with the sensor body 12 and with the transmissioncable 18 extending from the proximal end 13 of the sensor body 12.

In certain embodiments, the detector 16 is provided with a layer ofinsulating tape (not shown) for shielding the electronic components fromelectromagnetic interference. In certain embodiments, the shielding tapeis disposed between the body 12 and the protective pad 22.

Features of a Second Embodiment of the Sensor Assembly

A second sensor assembly embodiment will now be described with referenceto FIGS. 6-8. This sensor assembly 510 has an elongate body 512 (whichis seen only in the exploded view shown in FIG. 7) for supporting alight emitting source 514 (see FIGS. 6 and 7) and a detector 516 (seeFIG. 6). The elongate body 512 of this particular embodiment is providedby a length of two-sided tape (tape having adhesive provided on bothsides) which enables the body 512 to be fixed on one side to a skincontacting pad 524 (to be discussed below) and to hold in place othercomponents to be described below. The skilled person will recognize thatthe body 512 may be constructed of materials other than tape and fixedin place by other means which are known to the skilled person.

The LEDs and detectors described with reference to the first embodimentabove are suitable for use with this second embodiment. Wires 517 extendfrom the light emitting source 516 and run alongside wires 519 extendingfrom the detector 516. Both sets of wires 517 and 519 are encased intransmission cable 518. The light emitting source wires 517 provideelectrical power to the light emitting source 514. The detector wires519 provide electrical power to the detector 516 and carry signalsobtained by the detector 516 to a signal processor (not shown) when thesensor assembly 510 is in use.

The elongate body 512 has an opening 526 for the light emitting source514 (see FIGS. 6 and 7) and an opening 528 (which is seen only in FIG.6) for the detector 516. In this embodiment, the wires 517 and 519 arerigid and rest upon the elongate body 512 where they are held in placeby the adhesive of the top surface of the two-sided tape forming thebody 512. In certain embodiments, it is advantageous to fix these wiresto the elongate body 512 using adhesive or glue. In this arrangement,the light emitting source 514 and the detector 516 are held in placeabove their respective openings 526 and 528 in the elongate body 512.

In this particular embodiment, the detector 516 is protected fromextraneous radiofrequencies and electromagnetic interference by aradiofrequency/electromagnetic interference shield 515 which covers thetop and sides of the detector 516. The bottom of the shield 515 includesa Faraday cage window 515F which is seen more clearly in the inset 6′ ofFIG. 6. The Faraday cage window 515F allows entry of scattered lightoriginating from the light emitting source 514 for access to thedetector 516 while preventing entry of radiofrequency andelectromagnetic interference. Advantageously, in certain embodiments,the shield 515 is constructed of copper foil and a lead-free solder,such as Kester 331 OA neutral organic water soluble flux lead freesolder, is used to make the connections to the cable shield braid aswell as to connect the lead wires to the light emitting source 514 andthe detector 516. The manner of making electrical connections tocomponents housed within such a shield is well known to the personskilled in the art. A suitable shield blank for forming a shield boxaccording to one embodiment of the present invention is shown in FIG. 9.The shield blank 600 includes three separate panels 601, 602 and 603 forforming the floor of the shield box. Panel 601 is provided with aFaraday cage window as shown. Panels 611-617 form the side walls of theshield box and panels 621, 622 and 623 provide the sections of theceiling of the shield box.

This embodiment of the sensor assembly 510 includes a skin-contactingfilm 524. In certain embodiments this film 524 is formed of siliconerubber that forms a high performance elastomeric film. In someembodiments, the material used to form the skin-contacting film 524 aswell as the cover film 520 (to be described hereinbelow), is CLS3060 CLRtransparent medical grade self-bonding two component silicone rubberwhich is manufactured by Momentive Inc. of Columbus, Ohio, USA (formerlyGE Silicones). This material offers a convenient 1:1 mix ratio, hightensile strength and rapid cure time and may be provided with pigmentssuch as Polyone Stan-Tone 10FSP03 Titanium White or 90FSP06 Iron OxideBlack. These pigments are FDA approved pigments for silicone. Theskin-contacting film 524 and the cover film 520 can be prepared byliquid injection molding.

The skin-contacting film 524 is provided with openings that align withopenings 526 and 528 for the light emitting source 514 and detector 516,respectively to allow the emitted light to exit the sensor assembly,scatter off various anatomical structures within the hand at the lowerhalf of the palm or the ulnar edge of the palm with differentialabsorption by oxygenated and deoxygenated blood, followed by impingementupon the detector 516.

In this particular embodiment, the length of the entire elongate body512 is covered by an insulating strip 513 which serves to cover thelight emitting source 514 and the shield 515. In certain embodiments,the insulating strip is an insulating tape such as Kapton® tape which ismanufactured by Dupont Inc. Other insulating tapes are known to theskilled person and alternative insulating tapes may be selected for useas an insulating strip by the skilled person without undueexperimentation. The insulating strip 513 may also serve to hold theelongate body 512 in place on the skin-contacting film 524.Alternatively, an adhesive may be used to fix the lower surface of theelongate body 512 to the inner surface of the skin-contacting film 524.In other embodiments, both of these features are included. As describedabove for the first embodiment, additional adhesive films may beprovided to hold the transmission cable 518 in place on top of theskin-contacting film 524 in other embodiments (not shown).

The sensor assembly 510 is provided with a cover film 520 as notedabove. The cover film 520 has adhesive for fixing it to theskin-contacting film 524 such that both films 520 and 524 overlapsubstantially with each other and hold the body 512 in a fixed position.In this particular embodiment, the cover film 520 is formed of materialssimilar to those described above for forming the skin-contacting film524. In this particular embodiment, the cover film 520 is provided witha transparent window 523 which allows the position of the elongate body512 to be observed (as indicated by the position of the insulating strip513). As seen in FIG. 7, the cover film has a transverse fold 525 on theright side of the window 523 which can be pinched to facilitate removalof the backing sheet (not shown) which protects the adhesive layer priorto use. In certain embodiments, both the skin-contacting film 524 andthe cover film 520 are provided with backing sheets to protect theadhesive layers of these sheets prior to use, according to the mannerwhich is well known in the art.

Adhesion of the assembly to the skin is provided by the adhesive of theskin-contacting film and the elongate body of the sensor 512, isprevented from moving by adhesion provided by the cover film 520. Thesensor assembly 510 of this embodiment can be fixed to an appropriateposition on the lower half of the palm or the ulnar edge of the palm asdescribed in detail hereinbelow.

Placement and Operation of the Sensor Assembly

The placement and operation of the sensor assembly of the invention willnow be described with reference to FIGS. 10-14. Each placement promotesease of ambulation and mobility of the patient. The mobility of the handand flexing of the wrist does not interfere with the sensor or itsconnection to a signal processing unit. It should be understood thatwhile FIGS. 10-14 make reference to reference numerals of the embodimentof FIGS. 1-5, the sensor assembly embodiment of FIGS. 6-8 (with itsreference numbers in the 500 series) may be placed and operated in asimilar manner.

In one position, the sensor assembly 10 may be placed at the lower halfof the hand (in an orientation wherein the fingertips are at the top)between the center of the palm and the center of the back of the hand.In some embodiments, the sensor may be placed on the ulnar edge of thepalm. In other embodiments, the sensor is placed at a distance up to 50%from the ulnar edge of the palm UEP in either transverse direction(toward the palm or toward the back of the hand).

In one particular embodiment, with reference to FIG. 10, the sensorassembly 10 is attached to the palmar side of the ulnar edge of the palmUEP, along the longitudinal axis formed by the length of the fifth digitand generally orthogonal to the wrist crease WC. Some angling of thesensor assembly 10 with respect to the transverse axis of the wristcrease WC is permitted and the actual angle may vary according to theindividual user. This angle may be determined without any undueexperimentation or any exercise of any professional skill on the part ofthe medical practitioner or technician responsible for placing thesensor assembly on an individual for whom pulse oximetry readings aredesired. In some cases, the angle may be such that the sensor assemblylies at least partly above the capitate carpal bone. In such cases, theangling of the sensor assembly 10 may cause it to no longer overlap withsome of the other carpal bones, such as the pisiform carpal bone, forexample. The present inventors have surprisingly discovered that theparticular placement shown in FIG. 10 allows the sensor assembly 10 toacquire good signals while also avoiding stable fixation of the sensorassembly 10 at a location that avoids many kinds of incidental movementsof a fixed sensor such as wrist flexion, and contact with fingers duringgripping of objects in the palm of the hand.

The placement of the sensor assembly 10 on the palmar side of ulnar edgeof the palm UEP is shown in FIG. 10. It is seen that the body 12 of thesensor assembly 10 is placed at a position substantially parallel to thelongitudinal axis of the fifth digit on the palmar side of the ulnaredge of the palm UEP below the fifth digit 5D and above (and generallyorthogonal to) the wrist crease WC. For the sake of clarity, most of thefeatures of the sensor assembly 10 are omitted. An outline of theposition of the cover film 20 is shown with a broken line to indicatethe approximate location of this feature on the palmar side of the ulnaredge of the palm UEP. The transmission cable 18 is also shown extendingfrom a proximal end 13 of the body 12.

Another placement of the sensor assembly 10 on the palmar side of theulnar edge of the palm UEP is shown in FIG. 11. In this placement, thesensor is generally parallel with and overlapping a transverse palmaraxis which is generally defined by the pisiform, lunate and scaphoidcarpal bones and generally orthogonal to the axes defined by the lengthsof the metacarpals (some angling is permitted). In this placement,signals acquired by the sensor assembly 10 during use are not affectedby a gripping motion because the fingers, when flexed in a grippingmotion do not extend downward far enough to impact the sensor. Thisreduces the need for extensive signal averaging by the signal processorof the pulse oximetry system.

Another placement of the sensor assembly 10 on the ulnar edge of thepalm UEP is shown in FIG. 12. In this placement, the sensor is generallyparallel with the fifth digit. In this placement, as for the otherplacements described above, the signals acquired by the sensor assembly10 in this placement are not affected by a gripping motion.

Yet another placement of the sensor assembly 10 is shown in FIG. 13. Inthis placement, the sensor assembly 10 is attached to the lower half ofthe palm above the wrist crease WC along the axis formed by the scaphoidS, and trapezoid Tz carpal bones and the first digit 1D. The signalsacquired by the sensor assembly 10 in this placement are not affected bya gripping motion.

Shown in FIG. 14 is a view of the skeleton of the palmar side of theleft hand which indicates a placement of the main body 12 andtransmission cable 18 of the sensor assembly 10 which generallycorresponds to the position described for FIG. 10. It can be seen thatspecific bones of the skeleton of the hand lie beneath the body 12 ofthe sensor assembly 10. These bones, recited from the top and movinggenerally downward, are: the fifth metacarpal SMC, the fourth metacarpal4MC, the first metacarpal 1MC, the hamate H, the capitate C, thetrapezoid To, the scaphoid S, the trapezium Tz, the triquetrum Tq, thelunate L, and the pisiform P. Also indicated for context are the radiusR and the ulna U. Without being bound by any particular theory, it isbelieved that light emitted from the light source 14 passes (with someamount of scattering) through soft tissues of the palmar side of theulnar edge of the palm UEP with partial absorbance by oxygenated anddeoxygenated hemoglobin in the blood vessels and with additionalscattering from the harder surfaces of the bones described above withsubsequent detection by the detector 16. It is this detection ofscattered light that forms the basis of the pulse oximetry measurements.

Sensor Systems

Another aspect of the present invention is a system which includes thesensor described herein. Embodiments of such a system are shown in FIGS.15A and 15B. Features of the sensor have been described above and areomitted from FIGS. 15A and 15B for the sake of clarity. Referring now toFIG. 15A, the sensor assembly 1000 is connected to a monitor 1130 (suchas the NELLCOR™ monitor or the MASSIMO™ monitor mentioned above) whichprocesses signals obtained by the detector (not shown) and displays thedata. The connection of the sensor assembly 1000 to the monitor 1130 ismade by a transmission cable 1080 with plugs 1084 and 1086. In certainembodiments, the plugs are MASSIMO™ plugs as shown in FIG. 16 orNELLCOR™ plugs as shown in FIG. 17. The data acquired by the monitor1130 may be stored on a local computer workstation 1140, a removabledata storage unit 1150 or by an internet connection configured for clouddata storage 1160. An alternative embodiment shown in FIG. 15B issimilar to that of FIG. 15A with the exception that the transmissioncable 1080 is replaced with a wireless transmission system configured toprovide a wireless signal 1170 to the monitor 1130. In this embodiment,the sensor assembly 1000 is provided with a transmitter 1172 to send thewireless signal 1170 and the monitor 1130 is provided with a signalreceiver 1174 to receive the signal 1170. Wireless signal systems arecommercially available and can be adapted for use with this aspect ofthe invention, without undue experimentation.

Sensor Kits

Another aspect of the invention is a kit comprising the sensor describedherein. Advantageously, the kit includes instructions for attachment ofthe sensor to the hand. In some embodiments, the instructions specifyplacement to the lower half of the palm. In other embodiments,instructions for attachment of the sensor to the ulnar edge of the palmare provided. In certain embodiments, the sensor is encased inconveniently removable film to provide a package. Advantageously, thepackage is sterilized in certain embodiments. The package may beprovided with perforated tear lines to facilitate the removal of thesensor from the package without wrinkling of the cover film. The kit mayinclude a skin-contacting film and a cover film, each provided withbacking paper to protect the adhesive(s) disposed thereon. The kit mayalso include a transmission cable configured for attachment to thesensor at one end and to a signal processing unit at the other end.

Methods for Obtaining Pulse Oximetry Readings

Another aspect of the invention is a method for obtaining pulse oximetryreadings. The method includes the steps of: attaching a pulse oximetrysensor assembly to the palmar side of the ulnar edge of the palm betweenthe wrist crease and the base of the fifth digit, substantially parallelto a longitudinal axis defined by the fifth digit; connecting the sensorto a signal processing unit; and reading output data from the signalprocessing unit.

In another embodiment, the method for obtaining pulse oximetry readingsincludes the steps of attaching a pulse oximetry sensor to the palmarside of the ulnar edge of the palm adjacent the wrist crease andsubstantially parallel to a transverse axis defined by the pisiform,lunate and scaphoid carpal bones; connecting the sensor to a signalprocessing unit; and reading output data from the signal processingunit.

Advantageously, the sensor assembly is the pulse oximetry sensorassembly described herein. In certain embodiments, the method furtherincludes the step of storing the output data from the signal processingunit on a computer readable medium.

CONCLUDING STATEMENTS

It is to be understood that the words used in the present description ofexemplary embodiments are words of description rather than limitation,and that changes may be made within the purview of the appended claimswithout departing from the true scope and spirit of the invention in itsbroader aspects.

While various embodiments of the invention have been particularly shownand described, it will be understood by those skilled in the art thatvarious changes in form and details may be made therein withoutdeparting from the spirit and scope of the invention as defined by theappended claims.

All publications, patent applications, patents, internet sites and otherreferences mentioned herein are incorporated by reference in theirentirety. In case of conflict, the present specification, includingdefinitions, will control.

What is claimed is:
 1. A pulse oximetry sensor assembly configured forattachment to the ulnar edge of the palm, the sensor assemblycomprising: a) an elongate body comprising: a top surface; a lowersurface; a light emitting source; and a detector, the detectorconfigured to detect light originating from the light emitting sourceand scattered from a surface of the ulnar edge of the palm, wherein thedetector comprises: an interference shield configured to protect thedetector from radiofrequency/electromagnetic interference, theinterference shield comprising: a copper foil; and a Faraday cagewindow, the Faraday cage window allowing transmission of scattered lightto the detector; b) a skin-contacting film formed of elastomericmaterial, wherein the skin-contacting film comprises: a skin-contactingsurface comprising an adhesive; an inner surface, wherein the innersurface is in contact with the elongate body lower surface; a firstopening allowing transmission of light from the light emitting source tothe surface of the ulnar edge of the palm; and a second opening allowingtransmission of scattered light from the surface of the ulnar edge ofthe palm to the detector; c) an insulating tape comprising an insulatingmaterial, wherein the insulating tape is essentially aligned with theelongate body and covers the top surface of the elongate body; d) ameans for transmitting signals acquired by the detector to a signalprocessing unit, wherein the signals correspond to the scattered light;and e) a cover film formed of an elastomeric material and covering theinsulating tape, elongate body, and skin-contacting film, the cover filmcomprising: a transparent window allowing visualization of elongate bodyand insulating tape placement in relation to the skin-contacting filmand/or surface of the ulnar edge of the palm; and an adhesive to affixthe cover film to the insulating tape and skin contacting film.
 2. Thepulse oximetry sensor assembly of claim 1 wherein the elongate body isbetween about 30 mm to about 75 mm in length and about 8 mm to about 15mm in width.
 3. The pulse oximetry sensor assembly of claim 1, whereinthe distance between the center of the light emitting source and thecenter of the detector is between about 8 mm to about 10 mm.
 4. Thepulse oximetry sensor assembly of claim 1, wherein the cover film has alength of about 30 mm to about 75 mm and a width of about 10 mm to about33 mm.
 5. The pulse oximetry sensor assembly of claim 1, wherein thelight emitting source is a 600 and 900 nanometer wavelength red/infraredbi-color light emitting diode (LED).
 6. The pulse oximetry sensor ofclaim 1, wherein the means for transmitting signals is a transmissioncable in electrical communication with the detector.
 7. The pulseoximetry sensor assembly of claim 6 wherein the transmission cableterminates in a plug for connection to a signal processing unit.
 8. Thepulse oximetry sensor assembly of claim 6, wherein the elongate body,the light emitting source and the detector are disposable and detachablefrom the transmission cable.
 9. The pulse oximetry sensor assembly ofclaim 1, wherein the means for transmitting is a wireless signaltransmission system comprising a wireless transmitter in data transfercommunication with the detector and a wireless receiver in data transfercommunication with the signal processing unit.
 10. The pulse oximetrysensor assembly of claim 1, wherein the cover film extends outward fromthe skin contacting film to provide adhesion to skin of a palm, therebyholding the pulse oximetry sensor assembly in place on the ulnar edge ofa palm when the sensor is in use.
 11. A pulse oximetry systemcomprising: a) the pulse oximetry sensor assembly of claim 1, whereinthe means for transmitting signals acquired by the detector comprises atransmission cable, wherein the transmission cable is in electricalcommunication with the detector; and b) a signal processing unit inelectrical communication with a display unit for displaying pulseoximetry readings.
 12. The pulse oximetry system of claim 11, whereinthe signal processing unit is in data transfer communication with acomputer readable medium for storage of the pulse oximetry readings. 13.The pulse oximetry system of claim 11 wherein the transmission cable isdetachable from the sensor and the sensor is disposable.